Isolated bilateral lateral geniculate body necrosis following acute pancreatitis: A rare cause of bilateral loss of vision in a young femaleS Murugesan1, E Senthilkumar2, K Kumar1, VM Shah1
1 Department of Neuro-Ophthalmology, Aravind Eye Hospital and Post Graduate Institute of Ophthalmology, Kovai Medical Centre and Hospital, Coimbatore, Tamil Nadu, India
2 Department of Neurology, Kovai Medical Centre and Hospital, Coimbatore, Tamil Nadu, India
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/jpgm.jpgm_1134_21
Source of Support: None, Conflict of Interest: None
Keywords: Acute pancreatitis, bilateral visual loss, lateral geniculate body necrosis, paleo diet
Acute bilateral loss of vision presents a challenging diagnostic problem. Lesions of bilateral lateral geniculate body (LGB) causing this condition are a rare entity. Hemorrhagic infarction and osmotic demyelination are two possible theories postulated leading to this condition.
Here we report a case of a 22-year-old female, 10 months postnatal, who was recently on a paleo diet, presenting with sudden bilateral loss of vision following an acute episode of pancreatitis. She was diagnosed to have isolated bilateral LGB necrosis.
A 22-year-old obese female presented to our Neuro-Ophthalmic Department with complaints of sudden loss of vision of 1-week duration. She had a history of fever, abdominal pain, vomiting, and headache that was followed by giddiness and development of sudden loss of vision in both eyes. She was admitted and treated for the above symptoms elsewhere. Computed tomography (CT) of the abdomen revealed acute pancreatitis and magnetic resonance imaging (MRI) was essentially normal. Ophthalmologist opinion was obtained and after making a provisional diagnosis of bilateral optic neuritis, the patient was started on intravenous methylprednisolone for 3 days.
She did not have any improvement and was referred to us. Other than the history described earlier, she was obese with a body mass index (BMI) of 38.3 kg/m2, 10 months postnatal (full term normal delivery), and was on a paleo diet since 2 weeks. Her paleo diet mainly consisted of chicken, fish, eggs, and salads. She had no systemic illnesses. On examination, her visual acuity in right eye was hand movements and the left eye 20/600. Both eyes anterior segment and fundus examination were within normal limits except for sluggishly reacting pupils. Visual-evoked potential revealed prolonged latency in both eyes. Repeat MRI of the brain and orbit revealed bilateral subacute hemorrhagic necrosis with T1 shortening, punctate foci of blooming, and subtle enhancement with altered diffusivity noted within the region of LGBs with adjacent peri-lesional signal changes extending along optic pathway structures including optic tract [Figure 1].
She was referred to a multispecialty hospital where she was appropriately managed by a neurologist, hematologist, and gastroenterologist. Investigations revealed elevated total leukocyte count of 20400 cells/mm and serum amylase levels of 3744 U/L. Other blood examinations, such as renal function tests, serum electrolytes, complete blood counts, bleeding time, clotting time, and liver function tests were normal. Investigations for an infective etiology, including blood and urine cultures, hepatitis B surface antigen, anti-hepatitis C antibody titers, and 2D echo to rule out infective endocarditis were normal. CT chest revealed thin left pleural effusion with minimal pericardial effusion with coronavirus disease 2019 reporting and data system (CORADS) score of 1, CT abdomen confirmed acute pancreatitis (CT severity score of 4) [Figure 2], and after extensive blood work up including peripheral blood smear, disseminated intravascular coagulation profile, extractable nuclear antigens 6 profile, Coombs test, etc., she was diagnosed to have thrombotic microangiopathy (microvascular occlusion), bilateral LGB hemorrhagic infarct, acute pancreatitis with starvation, and dehydration shock. She was continued with steroid and other supportive treatment including systemic antibiotics.
On review, after discharge from the hospital, her MRI revealed resolution of fluid-attenuated inversion recovery hyperintensities in LGB bilaterally with residual blooming suggestive of old hemorrhagic gliosis [Figure 3]. Her visual acuity slightly improved in right eye to 20/600 and left eye to 20/250, and the fundi of both eyes showed temporal pallor of the discs.
Lesions in the post geniculate optic pathway lead to acute bilateral visual loss. In these lesions, the optic radiation, primary visual cortex, and associated visual cortices are the usual sites and trauma and posterior circulation stroke are the most common causes. An isolated lesion in bilateral LGB is an uncommon cause.
The reason for this isolated involvement of LGB has been poorly understood. The postulated mechanisms of isolated lesions of the LGB are hemorrhagic infarction,, and osmotic demyelination. Isolated lesions of the LGB are rare as the LGB is characterized by its high metabolic rate and dual blood supply.Anatomically, the anterior part of lateral geniculate is supplied by anterior choroidal artery (a branch of internal carotid artery) and the remaining part by the posterior choroidal artery (a branch of posterior cerebral artery). Therefore, disruption of the blood brain barrier in the distribution of anterior and posterior choroidal arteries leads to hemorrhagic infarcts in the lesions. One proposed mechanism for isolated LGB lesions is vascular occlusion because of micro angiopathies or arteritis. Another postulated mechanism of osmotic demyelination is because of the fact that because the LGB has a similar grid arrangement of grey and white matter as in the pons, it is considered as a site for extra pontine myelinolysis. The tight mesh-like arrangement between the neurons and oligodendroglia leads to difficulty in the expansion of the latter cells during rapid increase in sodium levels and hence, the cells exude osmolytes and thus lead to cell shrinkage. Myelinosis has been reported as a mechanism in three out of the eight reported cases, occurring in individuals with chronic debilitating conditions (alcoholism or liver disease) and after reversing the chronic hyponatremia rapidly.
Till date, all reported and documented cases of isolated LGB lesions are females, as also in our case. The dilemma whether this association is by chance or if females are more predisposed to such a complication still exists.
In our patient, who was a young 22-year-old female, there was isolated bilateral LGB necrosis following an attack of acute pancreatitis, similar to a case reported earlier. However, our case differs from that case as she did not have any retina findings. Two of the reported patients had history of alcohol intake, of which one presumed methanol consumption, one during pre-eclampsia, one (10-year-old child) after severe diarrhoea, one with syphilitic anterior choroidal arteritis, one after severe uterine hemorrhage, and lastly one with anaphylactic shock. Our patient did not give any of such history. Furthermore, our obese patient was recently on a paleo diet; whether this factor contributed to her condition has still not been fully understood. Sudden dietary shifts are known to up-regulate intracellular signaling pathways mediated by free intracellular calcium and protein kinase C (PKC), particularly in vascular smooth muscle cells called as “PKC syndrome” that can sensitize vascular smooth muscle cells to constrict.
Because there was no documented hyponatremia in our patient, and also because an infectious etiology could not be excluded conclusively, we postulated a vascular pathology, possibly hypo-perfusion because of shock following acute pancreatitis.
Our case demonstrates that shock may induce isolated ischemia of both LGBs resulting in acute loss of vision. Isolated lesions of the LGB should be considered, while evaluating for causes of acute loss of vision with normal fundus. Proper neurological and systemic evaluation should be done by the treating ophthalmologist, before starting high-dose steroids, in cases of bilateral acute loss of vision with a normal fundus in a young patient.
The authors would like to thank Dr. Shriram Varadharajan, Consultant, Department of Radiology, Kovai Medical Center and Hospital, Coimbatore for helping us diagnose this case.
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[Figure 1], [Figure 2], [Figure 3]